Department of Emerging Materials Science, DGIST, Daegu 42988, South Korea.
Sci Rep. 2016 Jul 15;6:29813. doi: 10.1038/srep29813.
The atomic-layered semiconducting materials of transition metal dichalcogenides are considered effective light sources with both potential applications in thin and flexible optoelectronics and novel functionalities. In spite of the great interest in optoelectronic properties of two-dimensional transition metal dichalcogenides, the excitonic properties still need to be addressed, specifically in terms of the interlayer interactions. Here, we report the distinct behavior of the A and B excitons in the presence of interlayer interactions of layered MoS2 crystals. Micro-photoluminescence spectroscopic studies reveal that on the interlayer interactions in double layer MoS2 crystals, the emission quantum yield of the A exciton is drastically changed, whereas that of the B exciton remains nearly constant for both single and double layer MoS2 crystals. First-principles density functional theory calculations confirm that a significant charge redistribution occurs in the double layer MoS2 due to the interlayer interactions producing a local electric field at the interfacial region. Analogous to the quantum-confined Stark effect, we suggest that the distinct behavior of the A and B excitons can be explained by a simplified band-bending model.
过渡金属二卤化物的原子层状半导体材料被认为是有效的光源，具有在薄型和柔性光电子学中的潜在应用和新颖功能。尽管人们对二维过渡金属二卤化物的光电性能非常感兴趣，但仍需要解决激子特性，特别是在层间相互作用方面。在这里，我们报告了存在层状 MoS2 晶体的层间相互作用时 A 和 B 激子的明显行为。微光致发光光谱研究表明，在双层 MoS2 晶体的层间相互作用下，A 激子的发射量子产率发生了急剧变化，而 B 激子的发射量子产率对于单层和双层 MoS2 晶体几乎保持不变。第一性原理密度泛函理论计算证实，由于层间相互作用在双层 MoS2 中发生了显著的电荷重新分布，在界面区域产生了局部电场。类似于量子限制的斯塔克效应，我们建议可以通过简化的能带弯曲模型来解释 A 和 B 激子的明显行为。
